The invention relates to bearings. More specifically, the invention relates to foil thrust bearings and foil journal bearings.
Foil journal bearings and foil thrust bearings are very attractive for high speed rotating machinery because they do not require oil-based lubrication and the maintenance demands of an oil-based lubrication system. Instead of using oil, the foil bearings use a process fluid such as air, methane, water, or gaseous or liquid hydrogen, nitrogen or oxygen.
Foil bearings that allow shaft rotation in one direction only, either clockwise or counterclockwise cause problems for high-speed machinery that requires rotation in both directions. For example, a high-speed motor might be required to turn a fan blade in a clockwise direction for blowing air and a counterclockwise direction for creating suction. Unidirectional foil bearings cannot be used in such a motor. The alterative, using separate motors for blowing and suction, is expensive and impractical.